(CNN) - As Halloween approaches, Americans rush to malls and shopping centers, credit cards in hand. Children are outfitted as ghosts, Disney characters, princesses and superheroes, while adults dress to impress with “sexy” witch, vampire or pirate garb. Cookies shaped like jack o’lanterns fly off the shelves along with bag after bag of packaged candy.

In American culture, Halloween has mostly become a reason for a good party.

So it may surprise you to learn that the roots of Halloween are religious. In fact, for Americans who practice contemporary Paganism, Halloween is one of the two most important religious holidays of the year. Known as Samhain (pronounced SOW-un), the holiday is modeled after the ancient Celtic festival that marked the beginning of winter.

In Ireland, Scotland and parts of what is now France, ancient people believed that on the night of Samhain, the veil between the living world and that of the dead grew thin. The festival was a time to honor one’s ancestors and to remember deceased family members, as well as to prepare for winter.

(CNN) - A protester who ridiculed the Muslim prophet Mohammed claims he was assaulted by a Muslim who was offended by the stunt, but a judge has sympathized with the alleged perpetrator, in a case that has drawn national attention.

Self-proclaimed atheist Ernie Perce marched in a Halloween parade in Mechanicsburg, Pennsylvania last October, dressed in a costume mocking Mohammed.

In a YouTube video he posted, Perce can be seen wearing a long fake beard, a white turban and green face paint, calling out provocative phrases like: "I am the prophet Mohammed! Zombie from the dead!" Perce and someone else in a zombie-themed pope costume are carrying a banner that reads "The Parading Atheists of Central Pennsylvania / Ghoulish – Godless – God-Awful."

As pumpkins, witches and faux cobwebs have taken over much of North America for Halloween, Clare Slaney-Davis is preparing an October 31 feast that some would consider much spookier, with table settings for her grandparents, a great-aunt and other relatives who have passed away.

As she and her living guests eat, they'll share stories and memories of loved ones they've lost.

Slaney-Davis, who is based in London, isn't preparing the feast for Halloween. Instead, she and pagans around the world are celebrating Samhain, the beginning of the pagan new year, a night when the veil between the worlds of the living and the dead is believed to be the thinnest of any time during the year.

That's why it's a night devoted to ancestors. "We honor them, and we recognize that we don't live in a world of people who are merely dead or alive," says Slaney-Davis, 46. "Ancestors are central to us."

“We don’t endorse that or we don’t celebrate that,” said Joe Hernandez, pastor of Worshipwalk Church in Los Angeles, which belongs to the conservative Pentecostal tradition. “People are celebrating the devil’s holiday.”

The CNN Belief Blog covers the faith angles of the day's biggest stories, from breaking news to politics to entertainment, fostering a global conversation about the role of religion and belief in readers' lives. It's edited by CNN's Daniel Burke with contributions from Eric Marrapodi and CNN's worldwide news gathering team.